Failure of Macroscopic Transport Models in Nanoscale Devices near Equilibrium

Abstract:The shrinking of the device dimensions below 100nm is pushing the classical TCAD tools like the drift-diffusion (DD) or hydrodynamic (HD) models to their limits. While the impact of the shrinking on the accuracy of the classical simulators has been investigated extensively for strong nonequilibrium, this is not the case for linear transport. Nekovee et al. have shown that even under equilibrium conditions the results of the momentum-based models might deviate from the exact solution of the Boltzmann transport equation (BTE) for devices due to built--in fields. This phenomenon is especially strong in nanoscale devices because of the small feature size and huge built--in fields. The impact of this effect on the accuracy of the DD and HD models is investigated for the first time in this work for nanoscale devices.